Modern surgery tends toward minimally invasive techniques whenever possible because they reduce pain and accelerate healing. Although often more complicated in some ways for the surgeon, minimally invasive techniques result in less trauma to the patient and less scarring because of much smaller incisions thereby promoting faster healing and reducing possibilities for infections. In general, minimally invasive surgeries involve making one or more small incisions at appropriate locations and inserting tubular devices through the incisions to the surgical site. Arthroscopic surgery, which typically occurs in an inter-articular space filled with fluid, allows orthopedists to efficiently perform procedures, including abrading and shaping both soft and hard tissue such as bone, cartilage and ligaments using special purpose tools designed specifically for arthroscopists. Among these instruments are graspers, biters, shavers and burrs. Many of these instruments include a hollow center and are coupled to a base connectable to a motor for operation of the instrument. Some of the instruments also include a rotatable inner tube having an abraded head at its distal end and fixed to an outer tube for rotational removal of the tissue. The space between the inner and outer tube is typically limited. As the tissue is being abraded, debris and fluid are generally drawn or sucked through the rotatable inner shaft which supports the burr. However, because the space is limited, debris can becomes lodged within the space between the outer and inner tube clogging up the instrument, causing poor visual clarity of the surgical site.
During use, some burrs are designed to fit through a small cannulae, which allows access to the surgical site. Some surgeons rely upon the cannulae to maintain good visibility with a joint structure. However, for good visibility one must provide for the effective removal of debris, which is continually produced during the abrading process. Providing a small gap within the abrading device for the removal may be inconsistent with this requirement.
Many rotary burrs have teeth or a cutting surface for shaping and removing damaged tissue. However, during use the cutting surface can damage surrounding healthy tissue which is in close proximity with the tissue being removed. The cutting edge of some burrs causes undesired movement, which also damages surrounding tissue. Because of the close proximity of healthy and unhealthy tissue, it is desireable to limit any undesired movement during use.
There is limited room to maneuver within a surgical site. Because of the close proximity, it is desired to maintain accessibility while limiting any visual obstructions from the surgical site. One requirement for good visibility is the effective removal of surrounding debris. Another is that the user have an unobstructed view of the active portion of the abrader in contact with the tissue and an unobstructed view of the tissue as it is abraded by the instrument.
In a typical device, removal of debris from the field is accomplished by aspirating debris from the surgical site via an inner rotating lumen, which is connected to an external vacuum source. However, the manner in which debris and fluid enter the lumen at the distal end of the instrument has a large effect on the volume of flow through the instrument and on the frequency with which the instrument clogs. Insufficient flow causes decreased visibility because of residual debris suspended in the intra-articular fluid. Clogging requires that the instrument be removed from the joint and “de-clogged.” The degree of difficulty of clog removal can impact the easy or difficulty of the procedure. Even if clog removal is easily accomplished, repeated removal of the instrument to de-clogging and reinserting the instrument can be problematic and may cause increased procedure times. Aspiration effectiveness, and therefore instrument design, can impact the burr efficiency.
There is a need for an improved burr which provides for improved visibility during surgery while not obstructing the cutting surface. In addition, there is a need for an improved burr with anti-clogging characteristics to improve the removal of debris from the surgical site, which enhances the surgeon's visibility in procedures where visibility is required.